DDhawk Tuesday, 12/20/11 07:18:51 PM Re: DDhawk post# 9580 Post # of 62524 Understanding 'efficiency' #'s... in answer to my own questions about this subject, here's a 'very good' expanded article on that same 114% story but w/ an explanation of how to digest (& compare) these numbers... "The new NREL cell shatters the quantum efficiencies of previous designs, posting a peak external quantum efficiency of 114 ± 1% and a peak internal quantum efficiency of 130%. In order to understand these numbers and how any power efficiency device can be more than "100 percent" efficient, you must understand the meaning of quantum efficiency (QE), which is overall quite different, but related to conversion efficiency (which will never be over 100 percent -- or even close to 100 percent -- in traditional physics).....Quantum efficiency is a measure of how many electrons come out of a cell for every photon that goes into the cell. Traditional silicon solar cells can achieve near 100 percent quantum efficiency at around 600 nm, but drop to around 80 percent on either end of the 500-1000 nm range (visible light is 380 to 740 nm). What this means is that the perfect "color" of light for silicon cells is orangish, while purple light can have a less than 45 percent conversion rate. As white light (sunlight) is a mixture of different wavelengths, the lower quantum efficiency of certain parts of the spectrum leads to lower average quantum efficiency. External efficiency directly uses the number of input photons and the number of output electrons from a device. Internal efficiency, by contrast, uses theory to adjust these numbers to account for losses due to reflection and absorption."*source; http://www.dailytech.com/New+Solar+Cell+Gives+Its+110+Percent+in+Efficiency/article23548.htm Strangely enough , it turns out I was thinking right on interpreting the 'quantum eff' aspect...the 'conversion eff' is the one we typically discuss...spec'd as 4.5% in this article.